For a device having two bodies such as a traditional box, a notebook or a tablet with a keyboard, the elastic element and the hook were usually used to fix the two bodies in a detachable manner in the early days. For example, an elastic hook is used to fix the covering body and the accommodated body of a traditional box. However, the elastic element easily abrades and loses the fastening ability after long-term use. Take the notebook as an example. The hook connected with an elastic element is used to fix the screen and the computer, but the hook may not return to the original position because of elastic fatigue.
Recently, some manufacturers develop a hinge, and the force to release the hinge is various with different opening angles. The internal ramp structure in the hinge is utilized to make the force applied on the opening position different with different opening angles. The notebook with this hinge is designed for the purpose that the force applied to open the screen is larger. Therefore, when the screen is closed, it is more difficult to open it and the screen can be stably fixed to the computer. However, the internal ramp structure is easily damaged when the applied force abrades the ramp. Consequently, it is important to develop a structure which is not only capable of fixing or releasing a device having two bodies but also capable of avoiding the elastic fatigue.